As an optical recording medium which can optically read out data, a disc-shaped recording medium (referred to as optical disc, hereinafter) such as a CD (Compact Disc) has been used. This kind of optical disc has large storage capacity and can realize random accessing. In reading out data which is optically recorded on an optical disc, since an optical read-out unit is not brought into contact with an optical disc, there is caused little fear that the recording medium and optical read-out unit are caused to be worn out or damaged due to contact between the recording medium and optical read-out unit, which may be raised in the case of using a magnetic tape as a recording medium. Since an optical disc has a protective layer made of synthetic resin formed on a surface thereof so as to protect the signal recording layer, there is little fear that data is lost by mistake as compared with the case using a magnetic tape. So, an optical disc which has much advantage as compared with a recording medium such as a magnetic tape is an excellent recording medium adopted for storing data processed in an information processing apparatus such as a personal computer.
Recently, recording and reproducing apparatuses using an optical disc capable of recording data such as a CD-R (Compact Disc-Recordable), CD-RW (Compact Disc-Rewritable) have been developed. Among those, there are recording and reproducing apparatuses which can easily perform writing processing corresponding to all standard formats used in compact discs such as a CR-ROM, CR-ROM/XA, CD-I, CD-DA. Having replaced a conventional magnetic tape or magnetic disc, a CD-R is arranged in a electronic apparatus and is used as a recording medium for recording data processed in the electronic apparatus.
As a standard concerning recording and/or reproducing data using an optical disc, there is known the UDF (Universal Disc Format) established by the OSTA (Optical Storage Technology Association) of the United States.
A recording medium conforming to the UDF employs the packet writing in writing data. Employing the packet writing, data is written in the packet configuration in which one link block and four Run-In areas are arranged before the data area and two Run-Out areas are arranged after the data area. So, seven blocks other than the data area are used as linking recording areas (referred to as Linking Area, hereinafter) being linking areas between adjacent packets.
In a file system conforming to additional recording of the UDF, management information of a directory and a file is indirectly managed using an FID (File Identifier Descriptor), a VAT (Virtual Allocation Table), a File Entry ICB (File Entry Information Control Block), etc., instead of being directly managed using a real recording position (real address).
The VAT is a technique to manage real addresses where files are really recorded and virtual addresses corresponding to the real addresses, forming a correspondence table. Employing the VAT, when additionally recording data to a recording medium, the recording medium is processed as if its arbitrary address on the recording medium is accessed so as to update or reproduce data.
That is, in the UDF, position information of directories and files is indirectly referred to. The VAT is freely arranged in the packet configuration, while a VAT ICB (Virtual Allocation Table Information Control Block) indicating the VAT is necessarily arranged at a position returning from the final sector recorded on a recording medium by the Linking Area. So, in the UDF, virtual addresses can be converted to real addresses by reading out the VAT indicated by the VAT ICB.
In the UDF, a string of logical sectors in which writing/reading out of data is performed is referred to as an extent, and start addresses of respective extents are retained as file information and are additionally recorded together with file system information to be updated.
Generally, in additionally recording image file data etc. to an optical disc, after image data is written, following a sequence of image data object, file information concerning the sequence of image data is written, as has been described above. So, since file information and file system information is recorded to the end of an extent, the file information and file system information cannot be recorded to a recording medium such as an optical disc unless writing processing of image data object is finished. In case there is no file information and file system information, or in case file information and file system information cannot be read out, since a reproducing apparatus cannot recognize a recording medium itself or respective data recorded on the recording medium, the recording medium cannot be used.
For example, in case of a recording medium such as a CD-R, when recording processing is interrupted due to discontinuance of drive power supply, uncovering of a cover arranged at a recording and reproducing apparatus which veils a recording medium, impact, etc. during recording processing, recording processing of file information cannot be completed. Thus, data which is recorded until recording processing is interrupted is caused to be unreadable, or an optical disc itself may be broken.
To cope with the situation in which thus recorded data is caused to be unreadable, there is proposed a restoration processing which restores such unreadable data to make the data readable to a certain extent. For example, there is a conventional restoration processing which retrieves file information forward and rerecord information in which damage is found. Employing this method, damaged data may be restored to be of the state before writing, while data which is interrupted during writing processing cannot be restored. That is, under the conventional restoration processing, once writing processing is interrupted, there is raised a problem that thus interrupted data cannot be accessed.
Furthermore, the larger the size of data such as a moving picture file or non-compressed still picture data becomes, the longer it takes to perform writing processing. Thus, there is raised much possibility of interruption of writing processing due to accidental factors during writing processing. Moreover, the larger the size of data becomes, the more lost data there is necessarily raised when writing processing is interrupted.
Especially, in case of recording original data which is not stored in advance, that is, recording real time data of such as moving pictures which is directly supplied from an image capturing apparatus, when an accident such as interruption of writing processing happens, not only data which is recorded during the interruption of recording processing is lost, but also data which is recorded before the interruption of recording processing is undesirably caused to be unreadable.